Chromium-nickel Steels Research Articles

Monitoring of relative magnetic permeability variation during cyclic bending testing of austenitic steel grade 10Kh18n10t samples

Cyclic bending testing of austenitic chromium-nickel steel grade 10Kh18N10T samples was carried out. Evalution of relative magnetic permeability showed its noticeable increase when the samples became fractured. This increase is related to deformation martensite appearance. Additional experiment showed, that deformation martensite formation starts before the actual destruction of the sample.

Surface Modification of Chromium–Nickel Steel by Electrolytic Plasma Nitriding Method

Electrolytic plasma nitriding is an attractive chemical heat treatment used to improve the surface properties of steel by implementing nitrogen saturation. This method is widely applied to steel and iron-based alloys operating under various operating conditions. In this work, using liquid-phase plasma nitriding technology, a nitrided layer was obtained on the surface of 40CrNi steel in electrolytes of different concentrations. The microstructure and phase composition of the nitrided layer were investigated and analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and we performed Vickers hardness and wear resistance tests using the ball-on-disc method. The microhardness and wear resistance of nitrided 40CrNi steel were significantly improved due to the lubricating properties of the ε-Fe2N phase formed on its surface.

Explicit correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

Explicit correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

Влияние режимов лазерной наплавки на геометрические размеры стального трека

Introduction. Laser surfacing is one of the leading trends in the field of additive technologies, which consists in layer-by-layer build of material using a laser as an energy source. To obtain a high-quality product, it is necessary to select the optimal building parameters correctly. The problem is that such optimization is necessary for all equipment, since minor differences in its characteristics can make significant changes in the parameters of layer-by-layer build. In order to determine the optimal build mode, it is enough to analyze the effect of various equipment parameters on the characteristics of single tracks. Therefore, the purpose of this work is to determine the most important parameters of laser radiation that affect the surfacing process and the optimal mode for building a single track of chromium-nickel steel. The work investigated single tracks obtained by laser surfacing of powder from austenitic chromium-nickel steel AISI 316L. The optimization factors included such characteristics as laser power, beam speed, flow rate of supplied powder and laser spot size. The wavelength of laser radiation was 1.07 μm. Research methods. To determine the quality and geometric dimensions of single tracks, the macrostructure of cross sections of specimens was studied using metallography and scanning electron microscopy methods. Results and discussion. It is established that the optimal mode for growing single tracks of steel AISI 316L is characterized by a laser radiation power of 1,250 W and a scanning speed of 25 mm/s. In this case, the optimal powder consumption rate is 12 g/min, and the laser spot size is 4.1 mm. The work shows that the powder consumption and laser spot size have the greatest influence on the coefficient of effective use of powder material. By changing it, the surfacing performance can be increased by 10–15 %.

Исследование кинетики формообразования деталей сферического подшипника скольжения из коррозионно-стойких сталей, полученных объемной штамповкой пористых заготовок

Introduction. Spherical powder sliding bearings are widely used in various branches of mechanical engineering. Therefore, the development of a promising method of production of spherical sliding bearing parts from powders of corrosion-resistant steels with specified properties is an urgent task. Purpose of work: is to study the kinetics of forming during cold die forging of spherical sliding bearing parts from stainless steel powder blanks, and to assess the effect of the chemical composition of lubricants and the design of the pressing tool on the structure and properties of the bearing outer ring. Materials from sprayed powders of stainless chromium-nickel steels obtained by cold die forging of sintered blanks coated with lubricants are studied in the work. The following research methods were used: mechanical tensile testing, metallographic studies and cold die forging process simulation. Results and its discussion. It is revealed that the resistance and work of deformation, as well as the kinetics of forming of the outer ring of the spherical sliding bearing are influenced by chemical composition of powders and lubricants, microstructure and mechanical properties of the blank material, configurations of the end surfaces of punches. The top and bottom edges of the outer bearing are most intensively sealed when the punch faces are made with a chamfer angle of 30–40 degrees. With an increase in the relative strain degree by height up to 0.30–0.35 its residual porosity amounted to 0.5–2.0 %. The features of definition of strain state and calculation of strain energy in the implementation of the offered method and the choice of technological parameters of the cold die forging process of sliding bearings parts are shown. A simple method for calculating and experimentally determining the coefficient of contact friction in the process of cold die forging of porous stainless steel blanks is developed, which allows to establish the effect of lubricant composition on the strain resistance at different values of the degree of radial deformation and to develop optimal methods of cold die forging of porous blanks in the production of parts of different complexity.

Changes in the Composition and Corrosion-Electrochemical Properties of the Chromium-Nickel Steel 03Cr18Ni11 During Implantation of Argon, Oxygen, and Nitrogen Ions

Changes in the Composition and Corrosion-Electrochemical Properties of the Chromium-Nickel Steel 03Cr18Ni11 During Implantation of Argon, Oxygen, and Nitrogen Ions

Characteristics of Si (C,N) Silicon Carbonitride Layers on the Surface of Ni-Cr Alloys Used in Dental Prosthetics.

Chromium- and cobalt-based alloys, as well as chrome-nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel-chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings.

PREDICTION OF ELECTROCHEMICAL PROCESSES OF LOCAL DISSOLUTION OF STAINLESS STEELS. PART 2. ANALYTICAL AND SIMULATION MODELING OF PROCESS DYNAMICS

To analyze the process of pitting corrosion, a state graph was used, which displays the possible states of local dissolution of chromium-nickel steels, taking into account the additional state "unstable passivation of macropitting". The developed analytical model for calculating the process before the formation of stable pitting is based on homogeneous Markov chains. The calculation of conditional probabilities of system changes from one possible state to another determines the time in the VisualStudio 2010 environment on the platform of NetFramework using the C# programming language. A comparison of the calculation of states with “unstable passivation of macropitting” (UPM) and without it allowed us to establish for stainless steels (12X18N10T, 10X17N13M2T, 08X22N6T) that the formation time of stable pitting taking into account UPM is less than the formation time without it, but more for 08X22N6T steel, which is due to the increased chromium content in its composition. A simulation model (SM) has been created, which is based on the Monte Carlo method, in which a random number generator is used to implement random processes of local dissolution due to SM, a sequence of states in which the system is located before its transition to a stable state is obtained. Also, due to this model, it became possible to consider the change in the potential of the system in the process of local dissolution of the studied steels. The use of two modeling approaches taking into account the state of the UPM allowed us to establish that IT is better consistent with experimental results both on a quantitative and qualitative level. An algorithm for selecting the values of the mode parameters is proposed, which became the basis for predicting the formation of macropitting processes. For citation: Vinogradova S.S. Prediction of electrochemical processes of local dissolution of stainless steels Part 2. Analytical and simulation modeling of process dynamics. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 119-126. DOI: 10.6060/ivkkt.20246706.6972.

ВЛИЯНИЕ РЕЖИМОВ ЛАЗЕРНОЙ НАПЛАВКИ ПОРОШКА КАРБИДА ВОЛЬФРАМА НА ХАРАКТЕРИСТИКИ ПОВЕРХНОСТИ СТАЛИ 12Х18Н10Т

An experimental study of the process of laser surfacing of fine tungsten carbide powder as part of a graphite paste coating on the surface of stainless chromium-nickel steel 12Kh18Ni10Ti was carried out. Surfacing was carried out in continuous conversion mode while ensuring processing speed, changing speed and line configuration.

Possibilities of Increasing the Durability of Punches Used in the Forging Process in Closed Dies of Valve Forgings by Using Alternative Materials from Tool Steels and Sintered Carbides.

This study refers to an analysis of the durability of forging tools applied in the second operation of producing a valve forging from the chromium-nickel steel, NC3015. Due to the extreme working conditions of the tools, caused by cyclic thermo-mechanical loads, the average durability of tools made from tool steel WLV (1.2365) equals about 1500 forgings. An in-depth, complex analysis was performed on the technology, using macroscopic tests combined with a measurement of the wear/allowance on the tool working surface through 3D scanning; microstructural tests by means of light microscopy; observations of the changes taking place on the working surface with a scanning electron microscope; microhardness measurements; and multi-variant numerical simulations. It was established that the key issue is the proper selection of the process technological parameters, such as the input material and tool temperature, friction, lubrication, tribological parameters, type of tool material, or punch design, because even small changes made to them significantly affect the service life of forging punches. Therefore, to increase the durability of the forging dies, alternative materials made of W360, as well as two high speed steels, S600 and S705, were applied. However, the implemented punch materials did not bring the assumed effect of increased durability, as the highest average durability of steel W60 equaled only 1500 forgings, whereas in the case of the tool steels, this was below 900 forgings. For this reason, at the further stage, punches with sintered carbide inserts were introduced, which made it possible to significantly improve the durability up to the level of as many as 20,000 forgings, which, at the same time, points to a promising direction of further studies on the use of materials and solutions of this type.

Possibilities of Increasing the Durability of Dies Used in the Extrusion Process of Valve Forgings from Chrome-Nickel Steel by Using Alternative Materials from Hot-Work Tool Steels.

This study refers to an analysis of the dies used in the first operation of producing a valve forging from chromium-nickel steel NC3015. The analyzed process of manufacturing forgings of exhaust valves is realized in the co-extrusion technology, followed by forging in closed dies. This type of technology is difficult to master, mainly due to the increased adhesion of the charge material to the tool substrate as well as the complex conditions of the tools' operations, which are caused by the cyclic thermo-mechanical loads and also the hard tribological conditions. The average durability of tools made from tool steel WLV (1.2365), subjected to thermal treatment and nitriding, equals about 1000 forgings. In order to perform an in-depth analysis, a complex analysis of the presently realized technology was conducted in combination with multi-variant numerical simulations. The obtained results showed numerous cracks on the tools, especially in the cross-section reduction area, as well as sticking of the forging material, which, with insufficient control of the tribological conditions, can cause premature wear of the dies. In order to increase the durability of forging dies, alternative materials made of hot work tool steels were used: QRO90 Supreme, W360, and Unimax. The preliminary tests showed that the best results were obtained for QRO90, as the average durability for the tools made of this steel equaled about 1200 forgings (with an increase in both the minimal and maximal values), with reference to the 1000 forgings for the material applied so far.

Applying the Hollomon-Jaffe parameter to predict changes in mechanical properties of irradiated austenitic chromium-nickel steels during isothermal exposure

<abstract> <p>The Hollomon-Jaffe parameter is widely used in metallurgy and materials science to characterize the behavior and predict the various metals' physical-mechanical properties under different temperature and time modes. The possibility of predicting changes in the mechanical properties of structural steels due to thermal influences has been studied. The paper presents the results of a study of the mechanical properties of the materials of the core components of the BN-350 reactor facility (RF) made of austenite chromium-nickel steel 12Cr18Ni10Ti (a spent fuel assembly's jacket) and 09Cr16Ni15M3Nb (an intro-channel displacer). The samples were studied both before and after radiation annealing. Annealing of steel samples at 550 ℃ reduced the yield strength and significantly restored the plasticity and ability of the material to strain hardening. The efficiency of post-radiation annealing of the materials increases with annealing temperature and leads to a transition to the reduction process. It was established that medium of high temperature annealing during heat treatment does not lead to significant changes in the mechanical properties of irradiated materials. The microstructure studied using a scanning electron microscope reasonably correlates with the results of mechanical tests. The possibility of using the Hollomon-Jaffe parameter to predict the properties of austenite chromium-nickel steel, which received damaging doses in the range from 12 to 59 dpa, was shown for the first time. Thus, for the first time, the unique coefficient (<italic>C</italic>) of the Holloman-Jaffe parameter for irradiated materials of chromium-nickel steel was experimentally determined, and dependencies characterizing the change in hardness of chromium-nickel steel on temperature and duration of post-radiation thermal exposure were established.</p> </abstract>

Solidification of quaternary X5CrNi18-10 alloy after laser beam welding: A phase-field approach

The austenitic stainless steel (X5CrNi18-10) is the most commonly used chrome-nickel steel, due to its high corrosion resistance. However, it faces the challenge of cracking events during post-laser-beam-welding dendritic solidification. These microstructural changes significantly impact the final mechanical properties. To contribute to a more precise understanding of the physical mechanisms of the appearance of cracking, the goal of this research is to investigate various aspects at the microscale influenced by process-specific extreme thermal conditions. A thermodynamic model of quaternary alloy configuration is used to study the micro-segregation behavior of alloying elements and resulting morphology based on the local thermal conditions. For this purpose, a multi-component and multiphase-field-based grand chemical potential model is used. It is observed that in addition to global processing conditions, local conditions are also important to consider and classify the morphology changes from columnar-dendritic to cellular along the liquidus isotherm of the weld pool.

Modeling and simulation of welded joints of SS304H & P91 Steels: A Review

Most of the structures are fabricated by welded joints in various manufacturing units because of low cost and high strength. Welding process is largely used in almost all manufacturing units. Welded joints usually subject to welding deformation patterns. Welding deformation may lead to low dimensional accuracy, shape and aesthetics of the product, strength of the welded joint. Welding of two different materials having different mechanical properties is called dissimilar welding. Dissimilar welded joints are commonly used in power plants to connect martensitic steel components and austenitic stainless steel piping systems. Our approach involves conducting dissimilar welding on P91 and SS304H steels, and subsequently assessing the properties of the welded joints using simulation software. A 3-D thermal elastic plastic finite element computational process is designed to accurately forecast welding deformation by numerical method. Numerical and experimental outcomes were compared in terms of temperature distributions during welding and in terms of distortion. P91 is a chromium-molybdenum alloy known for its remarkable strength and exceptional resistance to high temperatures. Alloy SS304H represents an adaptation of the chromium-nickel austenitic stainless steel. This variant, Grade 304H stainless steel, offers enhanced heat-resistant properties, increased tensile yield strength, and improved short- and long-term creep strength.

PREDICTION OF ELECTROCHEMICAL PROCESSES OF LOCAL DISSOLUTION OF STAINLESS STEELS. PART 1. SPECTRAL –FREQUENCY ANALYSIS OF POTENTIAL FLUCTUATIONS

The propagation of localized corrosion of stainless steels was investigated by spectral frequency analysis (HPA) of potential fluctuations in the modes of stationary and cyclic galvanostatic polarization. Corrosion-resistant austenitic and austenitic-ferritic chromium-nickel steels were studied: 12X18N10T, 10X17N13M2T, 08X22N6T, resistant to pitting corrosion, in an aqueous solution of 0.1 M NaCl with a cyanide-containing complexing agent, a corrosion stimulator - 0.01 g/l (K3[Fe(CN)6]). The studies were carried out in the range of low densities (0.5–10 µA /cm2) due to the small values of the limiting diffusion current density in oxygen. To find the time of the origin of macropittings, it is proposed to use the NAV of chronopotentiograms with their subsequent statistical processing (Fourier transform). It has been established that fluctuations in the boundary polarization regime are characteristic of the process of the origin, development and passivation of macropittings. In the mode of stationary galvanostatic polarization, frequency characteristics were studied in the range of 1.0 ± 0.5 µA/cm2. When analyzing spectral density graphs, it was found that the dominant frequency characterizes the time of formation of the macropitting, and the sections of the chronopotentiogram should be divided into sections with a duration of no more than 50-100 s. In non-stationary conditions of galvanostatic polarization in the range of 1.0-10 µA/cm2 in a cyclic mode, it was found that the processes of nucleation and passivation of macropittings can be traced with a changing value of the polarizing current. Based on the frequency range of chronopotentiograms, it was found that the average macropitting lifetime is 250-300 s (frequency range 0.033 - 0.004 Hz). The dominant frequencies are determined to identify the characteristic dependencies of the envelopes along the upper (fhg) and lower (fhg) boundaries of the potential change, based on them, an algorithm is proposed for selecting the values of the parameters of the prediction mode of the formation of macropitting processes.

ANALYSIS OF THERMODYNAMIC, STRESS-STRAIN, AND LOADED STATES OF CHROMIUM-NICKEL ALLOY WORKPIECES USING MACHINING PROCESS SIMULATION IN ADVANTAGE SOFTWARE

Machining difficult-to-cut materials, which include most high-alloy chromium-nickel steels and alloys, requires optimization of cutting parameters, correct application of tool materials, cutting blade geometry, etc. The particular relevance of a scientifically based analysis in addressing these issues is due to the large costs incurred in machining products made from such materials. The possibilities of experimental research to provide correct technological recommendations are quite limited. Instead, analytical modeling is imperfect due to the complexity of formalizing dynamic processes accompanied by fast-moving power, thermodynamic, and stress-strain phenomena. An effective research mechanism is simulation modeling of the cutting process of a hard-to-machine material (including in the AdvantEdge software). The article presents an analysis of the results of simulation studies of the influence of the main parameters of machining (depth and cutting speed) on the formation of power, thermodynamic, and stress-strain (including residual) parameters formed during cutting of chromium-nickel alloy Inconel IN 718. This analysis allows us to conclude the feasibility of choosing cutting parameters to ensure the effective performance properties of products made of this material

Raising the Wear Resistance of Chromium-Nickel Steel Surface-Hardened with Titanium Carbide Particles

Raising the Wear Resistance of Chromium-Nickel Steel Surface-Hardened with Titanium Carbide Particles

Study of the Effect of Selective Laser Melting Parameters on the Structure and Physico-Mechanical Properties of a Blank Made of Stainless Chromium-Nickel Steel

Currently, there are a number of additive technologies that are used in various industries (laser fusion of powder materials, electron beam melting, etc.). The formation of metal structures and products by methods of additive technologies occurs by adding a new layer of material and its further melting (sintering), ensuring the adhesion of each subsequent layer with the previous one in accordance with digital model data. The advantages of using and developing additive technologies include the possibility of using a wide range of materials, obtaining finished products with complex geometries, restoring and repairing damaged structures, as well as the possibility of applying protective and anticorrosive coatings. Metal powder materials with specified physical and mechanical properties are of crucial importance in additive manufacturing. The main requirements for such powders include requirements for their shape and size. The preferred particle shape is spherical, as it provides a more compact installation in a given volume and the necessary fluidity of the material, which is due to the low resistance in the supply systems of powder materials in 3D printers. The aim of the work is to study the influence of the parameters of the SLM printing process on the structure and mechanical properties of products made of 12Cr18Ni10Ti alloy. Samples obtained by selective laser melting were subjected to pycnometric and metallographic analysis. Based on the obtained microstructure images, a digital porosity analysis of the work piece under study was performed in the Thixomet Pro software package. The microhardness and acoustic characteristics were also measured over the entire section of the work piece under study. It was revealed that with an increase in the distance from the substrate (0...112 mm) in the transverse and longitudinal sections, the tendency remains to decrease the density values and increase the volume fraction of pores. It is shown that the acoustic parameter Dc can be used to control changes in the physical and mechanical properties of stainless chromium-nickel steel blanks obtained by selective laser melting.

Developing the optimal chemical composition of heat-resistant Cr-Ni steel for aerospace equipment

The object of research in this work is the processes of forming the microstructure and mechanical properties of heat-resistant steels depending on their chemical composition. The microstructure and high-temperature mechanical properties of austenitic heat-resistant chrome-nickel steels of the proposed chemical composition were investigated in the work. The microstructure study determined the grain size and topography of inclusions in steels. Based on the results of mechanical tests, a multifactorial experiment was planned, which made it possible to establish the relationship between the mechanical properties of steels with alloying elements selected as factors. The obtained regression equations were used to estimate the quantitative influence of each alloying element on the corresponding mechanical properties. Analysis of the results of the experiment made it possible to determine the optimal chemical composition of steel for gas turbine engines used in the aerospace industry, as well as in the metallurgy of titanium production. It is shown that the state of solid solution and heat-resistant niobium and molybdenum carbides (chromium carbides dissolve at a temperature of 950 °C) are an important factor that significantly affects the structure, mechanical, and service properties of heat-resistant steel. The austenite structure is provided by the required amount of nickel. The resulting indicators of heat resistance of steels of different compositions, tested at temperatures of 850 °C, 950 °C, and 1050 °C, proved the superiority of steel with a higher content of carbon and chromium and a lower content of nickel. The mechanism of steel strengthening and the influence of alloying with carbon, chromium, and nickel on it have been determined. The optimal chemical composition of heat-resistant steel on an iron-nickel basis for operation at a temperature of 950 °C has been established

Study of electrochemical properties of austenitic chromium-nickel steel 12Kh18N10T in concentrated sulfuric acid

Study of electrochemical properties of austenitic chromium-nickel steel 12Kh18N10T in concentrated sulfuric acid